ORBITALLY TUNED MODEL ANDSPECTRAL ANALYSIS

The BIO age model was improved by correlating the composite MS data with the
eccentricity record of insolation to create an astronomically calibrated age
model (the TCMS) (Fig. F6A,F6B,F6C;
Table T2).
The TCMS shifts the correlation in two directions; the events deeper than ~265
mcd are correlated to peaks older than in the BIO model, and events above ~265
mcd are generally correlated to peaks younger than in the BIO model (Fig. F6D),
although the unconformity at ~103 mcd suggested by the BIO model is slightly
older (2300-2100 ka) in the TCMS model. Average sedimentation rates are 8 cm/k.y.
with maximum rates in excess of 15 cm/k.y., occurring at 4400, 3900, 3000, and
2300 ka (Fig. F4B,F4C). There is an interval
of dark gray sedimentation associated with the 3000-ka (~147 mcd; ~132 mbsf)
and the 2300-ka (~115 mcd; ~104 mcd) events. Highest overall sedimentation rates
occur between 4300 and 2800 ka

The TCMS model has a dominant peak at 94 k.y. and a secondary peak at 119 k.y., compared to the 96 and 128 k.y. anticipated for the eccentricity curve (Fig. F5B). There is also a significant peak at 76 k.y. (Fig. F5B). Cross-spectral analysis reveals highest coherencies at 103- and 94.5-k.y. periodicities at a low phase lag (Table T4), with additional significant elevated coherencies at 130 and 77 k.y. (Fig. F5B; Table T4). There is only moderate coherency at the 41- and 19-k.y. cycles and very low coherency at 23-k.y. periodicity (Fig. F5B; Table T4).